Follow-up study of: (a) 74 hyperactive adults 22 to 29 years of age who were diagnosed as hyperactive fifteen years ago and who have not been treated with methylphenidate. (b) 50 hyperactive adults 17 to 22 years of age who were diagnosed as hyperactive ten years ago and who have been treated with methylphenidate for 6 months to 10 years. (c) 85 control subjects who will be matched with the above two groups with respect to age, I.Q. (WAIS), socioeconomic class and sex. Forty-five of the control subjects were obtained several years ago at the 5 year follow-up study; and forty are presently being tested for inclusion in a group to control for the methylphenidate-treated hyperactives. All hyperactive and control subjects are being assessed with respect to: (1) Psychiatric Status: comprehensive history; psychiatric interview, self-rating scale of psychopathology; (2) Alcohol and Drug Abuse (and non-medical drug use); (3) Antisocial Behavior (including court referrals, and a detailed stealing history); (4) California Psychological Inventory; (5) Tests of Self-Esteem; (6) Tests of Social Skills; (7) Work Record (competence at work; number and types of jobs; Employer's Rating Scale); (8) Motorcycle and Car Accidents; (9) School Guidance Questionnaire (methylphenidate-treated group and matched controls only); (10) Attitudes to professional help received (hyperactive groups only); (11) Physiological Measures: height, weight; pulse; blood pressure; EEG (methylphenidate-treated group only). This study will give us a clear picture of the final adult outcome of hyperactive children who were not treated with methylphenidate, and information on the efficacy and safety of stimulant therapy.